Pouch film laminate and secondary battery

Abstract

The pouch film laminate according to the present invention comprises a substrate layer, a gas barrier layer and a sealant layer laminated in that order, the substrate layer comprising a first substrate layer, a first adhesive layer and a second substrate layer laminated in that order, the first adhesive layer comprising more than 15 wt% and less than 60 wt% of metal oxide particles relative to the total weight of the first adhesive layer.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0015851 filed on February 6, 2023, and Korean Patent Application No. 10-2024-0009052 filed on January 19, 2024, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a pouch film laminate and a secondary battery produced by molding the same. [Background technology]

[0003] Secondary batteries are used in a wide range of fields, from small products such as digital cameras, DVD players, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes to large products requiring high output such as electric vehicles and hybrid vehicles, as well as power storage devices and backup power storage devices for storing surplus generated electricity and new renewable energy. Types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0004] A secondary battery can be manufactured by placing an electrode assembly, in which a positive electrode, a negative electrode, and a separator interposed between them are alternately stacked, in a battery case, injecting an electrolyte, and then sealing the battery case. Secondary batteries are classified into pouch types, can types, etc., depending on the material of the case that houses the electrode assembly.

[0005] A pouch-type secondary battery can be manufactured by pressing a flexible pouch film laminate to form a cup, placing an electrode assembly in the receiving space inside the cup, and sealing the seal. The pouch film laminate is formed of multiple layers, including a metal gas barrier layer on one side of which a polymer film such as polyethylene terephthalate is laminated, and a sealant layer made of a thermoplastic polyolefin resin is laminated on the other side. When the pouch-type battery case is sealed, the sealant layers are thermally bonded to each other to form the seal.

[0006] Recently, as the capacity of pouch-type secondary batteries has increased, the demand for pouches with excellent moldability has been increasing. When a thick gas barrier layer is formed to produce a pouch with excellent moldability, a problem arises in that the sealant layer does not easily melt during sealing of the pouch-type battery case. To solve this problem, methods have been used to increase the heat applied during sealing of the pouch-type battery case by increasing the sealing temperature and / or sealing time. However, increasing the sealing temperature above 220°C causes deformation due to melting of the base layer, and extending the sealing time increases the production time (tact time), resulting in reduced productivity. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above problems, and provides a pouch film laminate that can ensure both sealing quality and processability by preventing deformation of the seal portion and shortening the sealing time during the process of sealing a pouch-type battery case manufactured from the pouch film laminate, and a pouch-type battery case and pouch-type secondary battery manufactured by molding the same. [Means for solving the problem]

[0008] In one embodiment of the present invention, there is provided a pouch film laminate comprising a substrate layer, a gas barrier layer and a sealant layer laminated in that order, wherein the substrate layer comprises a first substrate layer, a first adhesive layer and a second substrate layer laminated in that order, and the first adhesive layer comprises more than 15 wt% and less than 60 wt% of metal oxide particles relative to the total weight of the first adhesive layer.

[0009] The metal oxide particles may contain at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. The metal oxide particles may have an average particle size D50 of 0.2 μm to 1 μm.

[0010] The first adhesive layer may contain metal oxide particles in an amount of 16% by weight to 59% by weight based on the total weight of the first adhesive layer.

[0011] The thickness of the first base layer may be 10 μm to 50 μm.The first base layer may include a polyester film.

[0012] The thickness of the first adhesive layer may be 1 μm to 10 μm.The first adhesive layer may contain at least one selected from the group consisting of urethane-based, epoxy-based, and acrylic-based polymers.

[0013] The thickness of the second base layer may be 10 μm to 50 μm.The second base layer may include a polyamide film.

[0014] The substrate layer may further include a second adhesive layer disposed between the second substrate layer and the gas barrier layer.

[0015] The thickness of the gas barrier layer can be from 30 μm to 100 μm.

[0016] The thickness of the sealant layer can be from 30 μm to 130 μm.

[0017] In another embodiment of the present invention, there is provided a pouch-type battery case manufactured by molding the above-mentioned pouch film laminate.

[0018] In another embodiment of the present invention, there is provided a pouch-type secondary battery including: a pouch-type battery case manufactured by molding the above-described pouch film laminate; and an electrode assembly housed in the pouch-type battery case. [Effects of the Invention]

[0019] In conventional pouch film laminates, although the first substrate layer prevents moisture from penetrating from outside the pouch, moisture from outside the pouch can pass through the first substrate layer and reach the second substrate layer due to limitations in its thickness and material. In this case, the moisture can easily be absorbed into the second substrate layer by forming hydrogen bonds with functional groups (e.g., amide structures) in the polymer contained in the second substrate layer. As a result, in the case of pouch-type battery cases manufactured by molding conventional pouch film laminates, when sealed at high temperatures to provide sufficient heat within the required production time, moisture absorbed in the second substrate layer within the pouch film laminate evaporates, causing bubbles to form in the second substrate layer. This can cause deformation and damage to the seal, resulting in a decrease in the insulating properties of the pouch.

[0020] To solve these problems, pouch-type battery cases manufactured from conventional pouch film laminates were sealed at low temperatures, which increased the sealing time and reduced the efficiency of the production process. Furthermore, to solve these problems, attempts to reduce the moisture content per unit weight of the pouch film laminate to less than 1,000 ppm resulted in problems such as difficulty in managing the storage of the pouch film laminate after production and high costs.

[0021] To solve the above-mentioned problems, the present invention provides a first adhesive layer disposed between a first substrate layer and a second substrate layer, containing more than 15 wt% but less than 60 wt% metal oxide particles. This allows the metal oxide in the first adhesive layer to be hydroxylated, removing moisture from the pouch before it is absorbed by the second substrate layer. Therefore, even when a pouch-type battery case manufactured from the pouch film laminate of the present invention is sealed at temperatures above 220°C, the generation of bubbles due to evaporation of moisture in the second substrate layer can be suppressed, preventing deformation of the seal and shortening the sealing time. As a result, the sealing quality and processability of the pouch-type battery case manufactured from the pouch film laminate of the present invention can be ensured, and the durability and lifespan characteristics of the pouch-type secondary battery can be improved. [Brief explanation of the drawings]

[0022] The drawings attached to the specification illustrate preferred embodiments of the present invention and, together with the above-described content of the invention, serve to provide a better understanding of the technical concept of the present invention, and the present invention should not be interpreted solely by the matters depicted in such drawings.

[0023] [Figure 1] 1 is a cross-sectional view of a pouch film laminate according to the present invention. [Figure 2] 1 is an exploded view of a pouch-type secondary battery according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0024] The advantages and features of the present invention, as well as methods for achieving them, will become clearer with reference to the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various different forms. However, the present embodiments are provided to fully disclose the present invention and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains, and the present invention is defined only by the scope of the claims. The same reference symbols refer to the same elements throughout the specification.

[0025] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in the sense that can be commonly understood by a person having ordinary knowledge in the technical field to which the present invention belongs. Furthermore, terms defined in commonly used dictionaries should not be interpreted ideally or excessively unless otherwise clearly defined.

[0026] The terms used in this specification are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless otherwise specified in the text. The words "comprises" and / or "comprising" used in this specification do not exclude the presence or addition of one or more other elements in addition to the elements mentioned.

[0027] In this specification, when a part is said to include a certain component, this does not mean that it excludes other components, but that it may further include other components, unless otherwise specified to the contrary.

[0028] In this specification, the phrase "A and / or B" means A, or B, or A and B.

[0029] In this specification, "%" means % by weight unless expressly indicated otherwise.

[0030] In this specification, D50 refers to the particle size corresponding to 50% of the cumulative volume in the particle size distribution curve. For example, D50 can be measured using a laser diffraction method. The laser diffraction method generally can measure particle sizes from the submicron range to several mm, and can provide results with high reproducibility and high resolution.

[0031] Pouch film laminate The pouch film laminate according to the present invention comprises a substrate layer, a gas barrier layer and a sealant layer laminated in that order, the substrate layer comprising a first substrate layer, a first adhesive layer and a second substrate layer laminated in that order, the first adhesive layer comprising more than 15 wt% and less than 60 wt% of metal oxide particles relative to the total weight of the first adhesive layer.

[0032] Fig. 1 is a cross-sectional view of a pouch film laminate 100 according to the present invention. Each component of the pouch film laminate 100 according to the present invention will be described in more detail below with reference to Fig. 1.

[0033] (1) Base material layer The substrate layer 110 is formed as the outermost layer of the pouch film laminate 100 to protect the secondary battery from external friction and impact. The substrate layer 110 is made of a polymer and can electrically insulate the electrode assembly from the outside.

[0034] The thickness of the base material layer 110 can be 5 μm to 100 μm, specifically 7 μm to 70 μm, and more specifically 25 μm to 60 μm. When the thickness of the base material layer 110 satisfies this range, the external insulation is excellent, the overall thickness of the pouch does not increase, and the energy density relative to the volume of the secondary battery is excellent.

[0035] The substrate layer 110 according to the present invention has a composite membrane structure formed by layers of two or more materials. In the composite membrane structure, an adhesive layer may be disposed between each layer. Specifically, the substrate layer 110 according to the present invention includes a first substrate layer 112, a first adhesive layer 116, and a second substrate layer 114, which are laminated in this order. Furthermore, the substrate layer 110 may further include a second adhesive layer 118 disposed between the second substrate layer 114 and the gas barrier layer 120.

[0036] The first substrate layer 112 may be a layer disposed as the outermost layer of the pouch film laminate, and the second substrate layer 114 may be a layer disposed between the first substrate layer 112 and the gas barrier layer 120. The first adhesive layer 116 may be a layer disposed between the first substrate layer 112 and the second substrate layer 114. The second adhesive layer 118 may be a layer disposed between the second substrate layer 114 and the gas barrier layer 120. The first substrate layer 112, the second substrate layer 114, the first adhesive layer 116, and the second adhesive layer 118 may be made of materials having different materials and / or physical properties. Interfaces may exist between each layer of the substrate layer 110, including the first substrate layer 112, the second substrate layer 114, the first adhesive layer 116, and the second adhesive layer 118. This means that each layer is different from the others and may be formed separately.

[0037] The first base material layer 112, the second base material layer 114, the first adhesive layer 116, and the second adhesive layer 118 will be described in more detail below.

[0038] 1) First base layer As described above, the first base layer 112 may be the outermost layer of the pouch film laminate, and in this case, the first base layer 112 may serve to prevent moisture from penetrating from outside the pouch.

[0039] The first base layer 112 may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber. Preferably, the first base layer 112 may include a polyester film having abrasion resistance and heat resistance. For example, the first base layer 112 may include at least one material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, but is not limited to this.

[0040] The thickness of the first base layer 112 can be 10 μm to 50 μm, specifically 10 μm to 40 μm, and more specifically 12 μm to 25 μm. When the thickness of the first base layer 112 satisfies the above numerical range, the insulation properties and formability of the pouch can be ensured, and the penetration of moisture into the inside of the pouch film laminate can be effectively suppressed. In addition, the overall thickness of the pouch does not increase, and the energy density relative to the volume of the secondary battery is excellent.

[0041] 2) Second base material layer The second substrate layer 114 may be a layer disposed between the first substrate layer 112 and the gas barrier layer 120. In this case, the second substrate layer 114 may serve to improve the formability of the pouch.

[0042] The second base material layer 114 may include a polyamide film. For example, the second base material layer 114 may include at least one selected from the group consisting of nylon 6, nylon 6,6, nylon MXD6 (polyxylylene adipamide), nylon 4, nylon 4,6, and nylon 4,10, but is not limited thereto. Preferably, the second base material layer 114 may include nylon 6, which has the advantage of improving the formability of the pouch due to the excellent stretchability of nylon 6.

[0043] The thickness of the second base layer 114 can be 10 μm to 50 μm, specifically 10 μm to 40 μm, and more specifically 15 μm to 35 μm. When the thickness of the second base layer 114 satisfies the above numerical range, the formability of the pouch can be ensured, and a decrease in the energy density relative to the volume of the secondary battery caused by an excessively thick pouch film laminate can be prevented.

[0044] The second base layer 114 may include an additive. By including an additive in the second base layer 114, it is possible to change the physical properties of the second base layer 114. For example, at least one of carbon fiber, glass fiber, and aramid fiber may be added as an additive to adjust the tensile strength of the second base layer 114.

[0045] 3) First adhesive layer The first adhesive layer 116 may be a layer disposed between the first substrate layer 112 and the second substrate layer 114. In this case, the first adhesive layer 116 may serve to adhere the first substrate layer 112 and the second substrate layer 114 to each other.

[0046] The first adhesive layer 116 may contain at least one selected from the group consisting of urethane-based, epoxy-based, and acrylic-based polymers, but is not limited thereto. Preferably, the first adhesive layer 116 contains a urethane-based polymer, which allows the first adhesive layer 116 to adhere to the first base material layer 112 and the second base material layer 114 and facilitates shaping and cutting.

[0047] The thickness of the first adhesive layer 116 can be 1 μm to 10 μm, specifically 2 μm to 8 μm, and more specifically 2 μm to 5 μm. When the thickness of the first adhesive layer 116 satisfies the above numerical range, sufficient adhesion between the first base material layer 112 and the second base material layer 114 can be ensured, and a decrease in the energy density relative to the volume of the secondary battery caused by an excessively thick pouch film laminate can be prevented.

[0048] Meanwhile, the first adhesive layer 116 includes metal oxide particles 140. The metal oxide particles 140 react with moisture to become hydroxylated, thereby removing the moisture that has passed through the first substrate layer 112 before it flows into the second substrate layer 114.

[0049] The metal oxide particles 140 may contain at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO. Preferably, the metal oxide particles 140 may contain at least one of CaO and MgO, which are favorable for hydroxylation with moisture.

[0050] The metal oxide particles 140 may be included in an amount of more than 15 wt % and less than 60 wt % based on the total weight of the first adhesive layer 116. Specifically, the metal oxide particles 140 may be included in an amount of more than 15 wt %, 16 wt % or more, or 20 wt % or more based on the total weight of the first adhesive layer 116, or less than 60 wt %, 59 wt % or less, or 50 wt % or less based on the total weight of the first adhesive layer 116. For example, the metal oxide particles 140 may be included in an amount of more than 15 wt % and less than 60 wt %, preferably 16 wt % to 59 wt %, and more preferably 20 wt % to 50 wt % based on the total weight of the first adhesive layer 116. If the metal oxide particles 140 contained in the first adhesive layer 116 are 15 wt % or less, moisture that flows into the second base material layer 114 cannot be sufficiently removed, and when a pouch-type battery case manufactured from the pouch film laminate is sealed at temperatures of 220°C or higher, the moisture contained in the second base material layer 114 evaporates, causing bubbles to form in the second base material layer, which in turn deforms and damages the seal, resulting in a decrease in the insulating properties of the pouch.If the metal oxide particles 140 contained in the first adhesive layer 116 are 60 wt % or more, the amount of metal oxide particles 140 in the first adhesive layer 116 becomes excessively large, resulting in a decrease in the adhesive strength between the first base material layer 112 and the second base material layer 114, which can cause peeling between the first base material layer 112 and the second base material layer 114 or improper lamination.

[0051] The average particle size D50 of the metal oxide particles 140 may be 0.2 μm to 1 μm, specifically 0.2 μm to 0.8 μm, and more specifically 0.3 μm to 0.7 μm. When the average particle size D50 of the metal oxide particles 140 satisfies this numerical range, the metal oxide particles 140 can be easily produced, the coating properties of the composition for forming the first adhesive layer 116 containing the metal oxide particles 140 can be ensured, and damage to the first substrate layer 112 and the second substrate layer 114 that are in direct contact with the first adhesive layer 116 can be prevented.

[0052] 4)Second adhesive layer The second adhesive layer 118 may be a layer disposed between the second substrate layer 114 and the gas barrier layer 120. In this case, the second adhesive layer 118 may serve to adhere the second substrate layer 114 and the gas barrier layer 120 to each other.

[0053] The second adhesive layer 118 may contain at least one selected from the group consisting of urethane-based, epoxy-based, and acrylic-based polymers, but is not limited thereto. Preferably, the second adhesive layer 118 contains a urethane-based polymer, which allows the second adhesive layer 118 to adhere to the second base material layer 114 and the gas barrier layer 120 and facilitates molding and cutting.

[0054] The thickness of second adhesive layer 118 can be 1 μm to 10 μm, specifically 2 μm to 8 μm, and more specifically 2 μm to 5 μm. When the thickness of second adhesive layer 118 satisfies the above numerical range, sufficient adhesion between second base material layer 114 and gas barrier layer 120 can be ensured, and a decrease in the energy density relative to the volume of the secondary battery caused by an excessively thick pouch film laminate can be prevented.

[0055] (2) Gas barrier layer The gas barrier layer 120 is laminated between the base layer 110 and the sealant layer 130 to ensure the mechanical strength of the pouch, block the entry and exit of gas or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the pouch-type battery case.

[0056] The gas barrier layer 120 may be formed of a metal, such as, but not limited to, a thin metal film containing one or more metals selected from the group consisting of aluminum (Al), copper (Cu), stainless steel (SUS), nickel (Ni), titanium (Ti), and invar.

[0057] According to one embodiment of the present invention, the gas barrier layer 120 may be formed of an aluminum alloy thin film. When the gas barrier layer 120 is formed using an aluminum alloy thin film, it is possible to ensure a certain level of mechanical strength, light weight, and the electrochemical properties of the electrode assembly and electrolyte, as well as heat dissipation. The aluminum alloy thin film may contain elements other than aluminum (Al). For example, the aluminum alloy thin film may contain one or more selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0058] As another example, the gas barrier layer 120 may be formed of a stainless steel thin film. Specifically, the gas barrier layer 120 may be manufactured by molding and / or processing the stainless steel thin film. The gas barrier layer 120 formed of stainless steel has relatively low thermal conductivity, which is effective in preventing or delaying heat diffusion to other cells during thermal runaway. Furthermore, the gas barrier layer 120 has relatively high toughness, which can suppress the occurrence of cracks in the pouch during use of the pouch-type battery. The stainless steel may contain elements other than iron (Fe), such as one or more selected from the group consisting of copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0059] The thickness of the gas barrier layer 120 can be 30 μm to 100 μm, specifically 30 μm to 90 μm, and more specifically 40 μm to 80 μm. When the thickness of the gas barrier layer 120 satisfies the above range, excellent moldability and gas barrier performance are achieved when forming the cup portion.

[0060] (3) Sealant layer The sealant layer 130 is thermally bonded to the sealing portion when the pouch-type battery case housing the electrode assembly therein is sealed, thereby completely sealing the inside of the pouch-type battery case. For this reason, the sealant layer 130 may be formed of a material with excellent thermal adhesive strength.

[0061] The sealant layer 130 may be formed of a material having insulating properties, corrosion resistance, and sealing properties. Specifically, since the sealant layer 130 is in direct contact with the electrode assembly and / or electrolyte inside the pouch-type battery case, it may be formed of a material having insulating properties and corrosion resistance. Furthermore, since the sealant layer 130 must completely seal the interior of the pouch-type battery case and prevent the transfer of substances between the inside and outside, it may be formed of a material having high sealing properties (e.g., excellent thermal adhesive strength). To ensure such insulating properties, corrosion resistance, and sealing properties, the sealant layer 130 may be formed of a polymer material.

[0062] The sealant layer 130 may be made of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber, and is preferably made of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0063] The thickness of the sealant layer 130 can be 30 μm to 130 μm, specifically 50 μm to 120 μm, and more specifically 70 μm to 100 μm. When the thickness of the sealant layer satisfies the above range, it is possible to ensure the seal strength of the sealed portion and the formability of the pouch film laminate.

[0064] Meanwhile, the sealant layer 130 according to the present invention may have a single film structure made of any one material. Alternatively, the sealant layer 130 may have a composite film structure formed by layers of two or more materials. Specifically, the sealant layer 130 may include a first sealant layer and a second sealant layer. In this case, the first sealant layer may be a layer disposed adjacent to the gas barrier layer, and the second sealant layer may be a layer disposed on the first sealant layer. The first sealant layer and the second sealant layer may be made of materials having different materials and / or physical properties. An interface may exist between the first sealant layer and the second sealant layer. This means that the first sealant layer and the second sealant layer are different layers and may be formed separately.

[0065] In order to ensure long-term adhesion between the gas barrier layer and the first sealant layer, it is particularly preferable that the first sealant layer is made of acid-modified polypropylene (PPa), which may be maleic anhydride polypropylene (MAH PP).

[0066] The second sealant layer may be formed of a material having insulating, corrosion-resistant, and sealing properties. Specifically, since the second sealant layer is in direct contact with the electrode assembly (260 in FIG. 2) and / or the electrolyte inside the accommodating space (224 in FIG. 2), it may be formed of a material having insulating and corrosion-resistant properties. Furthermore, since the second sealant layer must completely seal the interior of the battery case and prevent the transfer of materials between the interior and exterior, it may be formed of a material having high sealing properties. To ensure such insulating, corrosion-resistant, and sealing properties, the second sealant layer may be formed of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the second sealant layer may be formed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of unstretched polypropylene, acid-modified polypropylene, polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer. Here, the acid-modified polypropylene may be maleic anhydride polypropylene (MAH PP). More preferably, the second sealant layer may include cast polypropylene (CPP), which has heat sealability and high tensile strength.

[0067] Pouch-type secondary battery Next, the pouch-type secondary battery according to the present invention will be described.

[0068] The pouch-type secondary battery according to the present invention includes a pouch-type battery case manufactured by molding the above-mentioned pouch film laminate, and an electrode assembly housed in the pouch-type battery case. Specifically, the pouch-type secondary battery according to the present invention includes a pouch-type battery case housing an electrode assembly, the pouch-type battery case being manufactured by molding a pouch film laminate, the pouch film laminate including a substrate layer, a gas barrier layer, and a sealant layer laminated in that order, the substrate layer including a first substrate layer, a first adhesive layer, and a second substrate layer laminated in that order, the first adhesive layer including metal oxide particles in an amount of more than 15 wt% and less than 60 wt% based on the total weight of the first adhesive layer.

[0069] Hereinafter, each component of the pouch-type secondary battery of the present invention will be described in more detail with reference to FIG.

[0070] 2 is an exploded view of a pouch-type secondary battery 200 according to the present invention. As shown in FIG. 2, the pouch-type secondary battery 200 according to the present invention may include a pouch-type battery case 210, an electrode assembly 260, an electrode lead 280, an insulating portion 290, and an electrolyte (not shown).

[0071] (1) Pouch-type battery case The pouch-type battery case 210 can be manufactured by molding the pouch film laminate of the present invention. The pouch-type battery case 210 can house the electrode assembly 260 inside. The detailed structure and properties of the pouch film laminate are as described above, and a detailed description thereof will be omitted.

[0072] The pouch film laminate may be drawn and stretched using a punch or the like to manufacture the pouch-type battery case 210. As a result, the pouch-type battery case 210 may include a cup portion 222 and a receiving portion 224. The receiving portion 224 is a portion that receives the electrode assembly, and may refer to a bag-shaped receiving space formed inside the cup portion 222 as the cup portion 222 is formed.

[0073] According to one embodiment of the present invention, the pouch-type battery case 210 may include a first case 220 and a second case 230, as shown in Fig. 2. The first case 220 includes a receiving portion 224 that can receive the electrode assembly 260, and the second case 230 may cover the receiving portion 224 from above to prevent the electrode assembly 260 from falling out of the battery case 210. The first case 220 and the second case 230 may be manufactured by being connected to each other as shown in Fig. 2, but are not limited to this and may be manufactured in various ways, such as being separately manufactured.

[0074] In another embodiment of the present invention, when forming cup portions in a pouch film laminate, two symmetrical cup portions 222, 232 may be formed adjacent to each other by drawing one pouch film laminate. In this case, as shown in FIG. 2, the first case 220 and the second case 230 may be formed with the cup portions 222, 232, respectively. After the electrode assembly 260 is housed in the housing portion 224 of the cup portion 222 of the first case 220, the bridge portion 240 formed between the two cup portions 222, 232 may be bent so that the two cup portions 222, 232 face each other. In this case, the cup portion 232 of the second case 230 may house the electrode assembly 260 from above. Therefore, since two cup portions 222, 232 house one electrode assembly 260, a thicker electrode assembly 260 can be housed than when there is only one cup portion 222. Furthermore, by folding the pouch-type battery case 210, one end of the secondary battery 200 is formed, and the number of ends to be sealed in the subsequent sealing process can be reduced, thereby improving the processing speed of the pouch-type secondary battery 200 and reducing the number of sealing processes.

[0075] The pouch-type battery case 210 can be sealed with the electrode assembly 260 housed therein so that a portion of the electrode lead 280, i.e., a terminal portion, described below, is exposed. Specifically, when the electrode lead 280 is connected to the electrode tab 270 of the electrode assembly 260 and an insulating portion 290 is formed on a portion of the electrode lead 280, the electrode assembly 260 can be housed in the housing portion 224 provided in the cup portion 222 of the first case 220, and the second case 230 can cover the housing portion 224 from above. Then, an electrolyte is injected into the housing portion 224, and the seal portion 250 formed on the periphery of the first case 220 and the second case 230 can be sealed.

[0076] The sealing portion 250 may serve to seal the receiving portion 224. Specifically, the sealing portion 250 may be formed along the periphery of the receiving portion 224 to seal the receiving portion 224. The temperature at which the sealing portion 250 is sealed may be 180°C to 250°C, specifically 200°C to 250°C, and more specifically 210°C to 240°C. When the sealing temperature is within this range, the pouch-type battery case 210 can ensure sufficient seal strength through thermal bonding.

[0077] (2) Electrode assembly The electrode assembly 260 can be inserted into the pouch-type battery case 210 and sealed by the pouch-type battery case 210 after the electrolyte is injected.

[0078] The electrode assembly 260 may be formed by sequentially stacking a positive electrode, a separator, and a negative electrode. Specifically, the electrode assembly 260 may include two types of electrodes, a positive electrode and a negative electrode, and a separator interposed between the electrodes to insulate the electrodes from each other.

[0079] The positive and negative electrodes may each have a structure in which an active material slurry is applied to an electrode current collector in the form of a metal foil or metal mesh containing aluminum and copper. The slurry is typically formed by stirring a granular active material, auxiliary conductor, binder, conductive material, etc., in a solvent. The solvent can be removed in a subsequent process.

[0080] A slurry containing a mixture of an electrode active material, a binder, and / or a conductive material is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, which are then stacked on both sides of a separator to manufacture a predetermined shape of the electrode assembly 260. The electrode assembly 260 may be categorized into a stack type, a jelly roll type, a stack and folding type, etc., but is not limited thereto.

[0081] The electrode assembly 260 may include an electrode tab 270 .

[0082] The electrode tabs 270 are connected to the positive and negative electrodes of the electrode assembly 260, respectively, and protrude from the electrode assembly 260 to provide a path for electrons to move between the inside and outside of the electrode assembly 260. The electrode current collector included in the electrode assembly 260 may be composed of a portion coated with an electrode active material and an end portion, i.e., a plain portion, where the electrode active material is not coated. The electrode tabs 270 may be formed by cutting the plain portion or by connecting a separate conductive member to the plain portion by ultrasonic welding, for example. As shown in FIG. 2, the electrode tabs 270 may protrude in different directions from the electrode assembly 260, but are not limited thereto. They may protrude in various directions, such as protruding in parallel from one side in the same direction.

[0083] (3) Electrode lead The electrode lead 280 can supply electricity to the outside of the secondary battery 200. The electrode lead 280 can be connected to the electrode tab 270 of the electrode assembly 260 by spot welding or the like.

[0084] The electrode lead 280 is connected to the electrode assembly 260 and may protrude to the outside of the pouch-type battery case 210 via the sealing portion 250. Specifically, one end of the electrode lead 280 is connected to the electrode assembly 260, particularly the electrode tab 270, and the other end of the electrode lead 280 may protrude to the outside of the pouch-type battery case 210.

[0085] The electrode lead 280 may include a positive electrode lead 282 having one end connected to the positive electrode tab 272 and extending in the direction in which the positive electrode tab 272 protrudes, and a negative electrode lead 284 having one end connected to the negative electrode tab 271 and extending in the direction in which the negative electrode tab 271 protrudes. The other ends of both the positive electrode lead 282 and the negative electrode lead 284 may protrude to the outside of the battery case 210. This allows electricity generated inside the electrode assembly 260 to be supplied to the outside. In addition, since the positive electrode tab 272 and the negative electrode tab 271 protrude in various directions, the positive electrode lead 282 and the negative electrode lead 284 may also extend in various directions. The positive electrode lead 282 and the negative electrode lead 284 may be made of different materials. That is, the positive electrode lead 282 may be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 284 may be made of the same copper (Cu) material as the negative electrode current collector or a copper material coated with nickel (Ni). A portion of the electrode lead 280 protruding outside the battery case 210 serves as a terminal portion and can be electrically connected to an external terminal.

[0086] (4) Insulation section The insulating portion 290 prevents electricity generated from the electrode assembly 260 from flowing to the battery case 210 via the electrode lead 280, thereby maintaining the seal of the battery case 210. To this end, the insulating portion 290 may be formed of an insulator that is electrically non-conductive and does not easily pass electricity. Generally, the insulating portion 290 is formed of a relatively thin insulating tape or film that is easily attached to the electrode lead 280, but is not limited thereto, and any material that can insulate the electrode lead 280 may be used.

[0087] The insulating part 290 may be disposed to surround the outer circumferential surface of the electrode lead 280. Specifically, at least a portion of the electrode lead 280 may be surrounded by the insulating part 290. In this case, the insulating part 290 may be disposed between the electrode lead 280 and the pouch-type battery case 210. The insulating part 290 may be disposed only in the seal part 250 where the first case 220 and the second case 230 of the pouch-type battery case 210 are thermally sealed, and the electrode lead 280 may be bonded to the battery case 210.

[0088] (5) Electrolyte The pouch-type secondary battery 200 according to the present invention may further include an electrolyte (not shown) injected into the pouch-type battery case 210. The electrolyte is used to move lithium ions generated by an electrochemical reaction of the electrodes during charging / discharging of the secondary battery 200, and may include a non-aqueous organic electrolyte solution that is a mixture of a lithium salt and an organic solvent, or a polymer using a polymer electrolyte. Furthermore, the electrolyte may include a sulfide-based, oxide-based, or polymer-based solid electrolyte, and such a solid electrolyte may have flexibility that makes it easily deformable under external force.

[0089] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative to aid in understanding the present invention and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical concept of the present description, and it goes without saying that such changes and modifications fall within the scope of the appended claims.

[0090] Examples and Comparative Examples Example 1: Manufacturing of a pouch film laminate A first adhesive layer was prepared, measuring 266 mm wide, 50 mm long and 3 μm thick, containing 20 wt % of CaO particles (average particle size D50: 0.5 μm) relative to the total weight of the first adhesive layer (urethane film).

[0091] On one side of an aluminum alloy thin film measuring 266 mm wide, 50 mm long, and 60 μm thick, a second adhesive layer (urethane film) measuring 266 mm wide, 50 mm long, and 3 μm thick, a nylon film (second base layer) measuring 266 mm wide, 50 mm long, and 25 μm thick, the first adhesive layer, and a polyethylene terephthalate (PET) film (first base layer) measuring 266 mm wide, 50 mm long, and 12 μm thick were laminated in this order. A polypropylene (PP) film measuring 266 mm wide, 50 mm long, and 80 μm thick was coextruded on the other side of the aluminum alloy thin film. As a result, a pouch film laminate was produced with a structure in which polypropylene film / aluminum alloy thin film / second adhesive layer / nylon film / first adhesive layer / polyethylene terephthalate film were laminated in this order.

[0092] Here, the polypropylene film is a sealant layer, the aluminum alloy thin film is a gas barrier layer, and the second adhesive layer, nylon film, first adhesive layer and polyethylene terephthalate film are base layers.

[0093] Example 2: Manufacturing of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained CaO particles in an amount of 30 wt % based on the total weight of the first adhesive layer.

[0094] Example 3: Preparation of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained 40 wt % of CaO particles relative to the total weight of the first adhesive layer.

[0095] Example 4: Preparation of a pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained CaO particles in an amount of 50 wt % based on the total weight of the first adhesive layer.

[0096] Comparative Example 1: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer did not contain CaO particles.

[0097] Comparative Example 2: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained CaO particles in an amount of 5 wt % based on the total weight of the first adhesive layer.

[0098] Comparative Example 3: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained CaO particles in an amount of 10 wt % based on the total weight of the first adhesive layer.

[0099] Comparative Example 4: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained CaO particles in an amount of 15 wt % based on the total weight of the first adhesive layer.

[0100] Comparative Example 5: Production of pouch film laminate A pouch film laminate was produced in the same manner as in Example 1, except that the first adhesive layer contained CaO particles in an amount of 60 wt % based on the total weight of the first adhesive layer.

[0101] Comparative Example 6: Production of pouch film laminate A second adhesive layer was prepared, measuring 266 mm wide, 50 mm long and 3 μm thick, containing 30 wt % of CaO particles (average particle size D50: 0.5 μm) relative to the total weight of the second adhesive layer (urethane film).

[0102] On one side of the aluminum alloy thin film (266 mm wide, 50 mm long, and 60 μm thick), the second adhesive layer, a nylon film (266 mm wide, 50 mm long, and 25 μm thick) (second base layer), a first adhesive layer (urethane film) (266 mm wide, 50 mm long, and 3 μm thick), and a polyethylene terephthalate (PET) film (1st base layer) (266 mm wide, 50 mm long, and 12 μm thick) were laminated in this order. A polypropylene (PP) film (266 mm wide, 50 mm long, and 80 μm thick) was co-extruded on the other side of the aluminum alloy thin film. As a result, a pouch film laminate was produced with a structure in which polypropylene film / aluminum alloy thin film / second adhesive layer / nylon film / first adhesive layer / polyethylene terephthalate film were laminated in this order.

[0103] Here, the polypropylene film is a sealant layer, the aluminum alloy thin film is a gas barrier layer, and the second adhesive layer, nylon film, first adhesive layer and polyethylene terephthalate film are base layers.

[0104] Comparative Example 7: Production of pouch film laminate A third adhesive layer was prepared, measuring 266 mm wide, 50 mm long, and 3 μm thick, and containing 30 wt % of CaO particles (average particle size D50: 0.5 μm) relative to the total weight of the third adhesive layer (urethane film).

[0105] On one side of an aluminum alloy thin film measuring 266 mm wide, 50 mm long, and 60 μm thick, a second adhesive layer (urethane film) measuring 266 mm wide, 50 mm long, and 3 μm thick, a nylon film measuring 266 mm wide, 50 mm long, and 25 μm thick, a first adhesive layer (urethane film) measuring 266 mm wide, 50 mm long, and 3 μm thick, and a polyethylene terephthalate (PET) film measuring 266 mm wide, 50 mm long, and 12 μm thick were laminated in this order. The third adhesive layer was laminated on the other side of the aluminum alloy thin film, and a polypropylene (PP) film measuring 266 mm wide, 50 mm long, and 80 μm thick was co-extruded. As a result, a pouch film laminate was produced with a structure in which polypropylene film / third adhesive layer / aluminum alloy thin film / second adhesive layer / nylon film / first adhesive layer / polyethylene terephthalate film were laminated in this order.

[0106] Here, the polypropylene film is a sealant layer, the aluminum alloy thin film is a gas barrier layer, and the second adhesive layer, nylon film, first adhesive layer and polyethylene terephthalate film are base layers.

[0107] Experimental Example 1: Measurement of moisture content per unit weight of pouch film laminate and evaluation of adhesion between first and second base layers The pouch film laminates produced in Examples 1 to 4 and Comparative Examples 1 to 7 were stored at 60°C and 90% relative humidity for two hours, and then the moisture content per unit weight of the pouch film laminate was measured. Specifically, the pouch film laminates were cut into 50mm x 40mm pieces and stored at 60°C and 90% relative humidity for two hours. The moisture content per unit weight of the pouch film laminate (μg / g = ppm) was then measured at 150°C using a Karl Fischer moisture analyzer. The measurement results are shown in Table 1 below.

[0108] In addition, the pouch film laminate was stored at a temperature of 60°C and a relative humidity of 90% for 2 hours, and the degree of adhesion between the first and second base layers was evaluated by visually checking whether or not there was peeling between the first and second base layers. The results are shown in Table 1 below: ○: Delamination occurred between the first and second base materials. ×: No delamination occurs between the first base material layer and the second base material layer.

[0109] Experimental example 2: Evaluation of seal deformation in pouch-type battery cases Two pouch film laminates were prepared for each of Examples 1 to 4 and Comparative Examples 1 to 7. Each pouch film laminate was then cut to a size of 266 mm wide and 200 mm long, and then folded in half to a size of 133 mm wide x 200 mm long so that the sealant layers were in contact. The edges of the long sides (200 mm) were then sealed under the following three conditions to produce pouch-type battery cases.

[0110] -Seal bar area 200mm x 8mm, seal for 1.8 seconds at 210℃ and cylinder pressure 0.1MPa -Seal bar area 200mm x 8mm, seal for 1.8 seconds at 230℃ and cylinder pressure 0.075MPa

[0111] Next, each of the pouch-type battery cases sealed at different temperatures was visually inspected to see if any bubbles had formed in the second base material layer disposed at the sealed portion, causing deformation of the sealed portion. The results are shown in Table 1 below: ○: Air bubbles cause deformation of the seal ×: No bubbles are generated and the seal portion is not deformed.

[0112] [Table 1]

[0113] According to Table 1, in Examples 1 to 4, in which the first adhesive layer contains more than 15 wt % and less than 60 wt % metal oxide particles, even when sealed at a temperature of 230°C, no air bubbles are generated in the second substrate layer, the sealed portion of the pouch-type battery case does not deform, and it can be confirmed that the lamination between the first substrate layer and the second substrate layer is excellent.

[0114] On the other hand, in the case of Comparative Examples 1 to 4, in which the first adhesive layer contains 15% by weight or less of metal oxide particles, a relatively large amount of moisture is present in the second base material layer, and when sealing is performed at a temperature of 230°C, it is confirmed that air bubbles are generated in the second base material layer, causing deformation of the seal portion of the pouch-type battery case.

[0115] In addition, in the case of Comparative Example 5, in which the first adhesive layer contained 60% or more by weight of metal oxide particles, the adhesive strength between the first substrate layer and the second substrate layer in the pouch film laminate decreased, peeling occurred between the first substrate layer and the second substrate layer, and it was confirmed that lamination was not performed properly.

[0116] Furthermore, in the case of Comparative Examples 6 and 7, in which the metal oxide particles are contained in an amount of more than 15 wt % and less than 60 wt % not in the first adhesive layer laminated between the first substrate layer and the second substrate layer, but in the second adhesive layer laminated between the second substrate layer and the gas barrier layer, or in the third adhesive layer laminated between the gas barrier layer and the sealant layer, a relatively large amount of moisture is present in the second substrate layer, and when sealing is performed at a temperature condition of 230°C, bubbles are generated in the second substrate layer, and it is confirmed that the seal portion of the pouch-type battery case is deformed. [Explanation of symbols]

[0117] 100 Pouch film laminate 110 Base material layer 112 1st base layer 114 Second base layer 116 1st adhesive layer 118 Second adhesive layer 120 Gas barrier layer 130 Sealant Layer 140 Metal oxide particles 200 Pouch-type secondary battery 210 Pouch-type case 220 Case 1 222 Cup section 224 Storage Unit 230 Case 2 232 Cup section 240 Bridge section 250 Seal part 260 Electrode assembly 270 Electrode Tab 271 Negative electrode tab 272 Positive electrode tab 280 Electrode Lead 282 Positive lead 284 Negative lead 290 Insulation

Claims

1. A pouch film laminate comprising a base layer, a gas barrier layer, and a sealant layer laminated in this order, the substrate layer includes a first substrate layer, a first adhesive layer, and a second substrate layer laminated in this order; A pouch film laminate, wherein the first adhesive layer contains metal oxide particles in an amount of more than 15 wt % and less than 60 wt % based on the total weight of the first adhesive layer.

2. The pouch film laminate according to claim 1, wherein the metal oxide particles include at least one selected from the group consisting of CaO, MnO, SrO, MgO, and ZnO.

3. The pouch film laminate according to claim 1, wherein the metal oxide particles have an average particle size D50 of 0.2 μm to 1 μm.

4. The pouch film laminate according to claim 1, wherein the first adhesive layer contains metal oxide particles in an amount of 16% by weight to 59% by weight based on the total weight of the first adhesive layer.

5. The pouch film laminate according to claim 1, wherein the thickness of the first base layer is 10 μm to 50 μm.

6. The pouch film laminate according to claim 1 , wherein the first base layer comprises a polyester-based film.

7. The pouch film laminate according to claim 1, wherein the first adhesive layer has a thickness of 1 μm to 10 μm.

8. The pouch film laminate according to claim 1 , wherein the first adhesive layer contains at least one selected from the group consisting of urethane-based, epoxy-based, and acrylic-based polymers.

9. The pouch film laminate according to claim 1, wherein the second base layer has a thickness of 10 μm to 50 μm.

10. The pouch film laminate according to claim 1 , wherein the second substrate layer comprises a polyamide-based film.

11. The pouch film laminate according to claim 1 , wherein the base layer further comprises a second adhesive layer disposed between the second base layer and the gas barrier layer.

12. 2. The pouch film laminate according to claim 1, wherein the gas barrier layer has a thickness of 30 μm to 100 μm.

13. 2. The pouch film laminate according to claim 1, wherein the sealant layer has a thickness of 30 μm to 130 μm.

14. A pouch-type battery case including a formed pouch film laminate, A pouch-type battery case, wherein the pouch film laminate is the pouch film laminate according to any one of claims 1 to 13.

15. a pouch-type battery case including a molded pouch film laminate; an electrode assembly housed in the pouch-type battery case; A pouch-type secondary battery comprising: The pouch film laminate is the pouch film laminate according to any one of claims 1 to 13, wherein the pouch film laminate is a pouch-type secondary battery.

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